1. Field of the Invention
The invention relates to a magnetic recording device with a fixed excitation rotating head which can especially be used in magnetic tape recording equipment such as video tape recorders in which the recordings are made in the form of lines of data arranged crosswise to the direction in which the tape runs.
2. Discussion of Background
Such a head can be used to record (write and/or read) analog or digital signals on a tape or any other magnetic medium as, for example, in a video tape recorder. A major feature of magnetic heads of this type is that the recording is done on the tape through mechanical motion in two dimensions: the running of the tape and a scanning operation by a rotating part.
It is known in the technology that high-velocity and high-density recording is done by rotating drums on which there are several magnetic heads which scan the tape along parallel tracks whose direction is oblique in relation to the length of the tape.
The heads are excited by means of a transformer whose magnetic circuit may be partly rotating and partly fixed.
Heads are also known in which the gap is formed by a fixed pole and a rotating pole.
The object of the invention relates to a configuration of a set of magnetic heads, the gaps of which are on a cylindrical part which can rotate and which have one (or more) fixed, common coils.
The advantage of the invention presented is that it eliminates the coils of the heads of the rotating drum. A set of heads of this type costs less to manufacture and is also less bulky.
As compared to a head where the gap is formed by a fixed pole and a rotating pole, the head according to the invention has the advantage that the width of the gap is not limited by the mechanical motion of one of the poles, which would necessitate a substantial distance between the poles.
It is therefore possible to make very narrow gaps and thus maintain high recording resolution.
In the invention, the gaps that separate the fixed part from the rotating part can be made in such a way that the efficiency of the head is not reduced. To this end, the area of the gaps is increased so as to diminish their reluctance. Moreover, a magnetic lubricant can be put in these gaps, for example, a product commercially known under the trademark of "Ferrofluid".